diff --git a/docs/agents/tasks/04-time-scheduler.md b/docs/agents/tasks/04-time-scheduler.md
index ffc0273..6a4fa20 100644
--- a/docs/agents/tasks/04-time-scheduler.md
+++ b/docs/agents/tasks/04-time-scheduler.md
@@ -67,18 +67,19 @@
 - 已建立 idle thread，所有普通线程 sleep/wait 时由 idle 承接 CPU。
 - 已提供 `sched_sleep()`，线程可以睡眠指定 tick 数并被 timer 唤醒。
 - 已提供 `wait_queue_init()`、`wait_queue_sleep()`、`wait_queue_wake_one()` 和 `wait_queue_wake_all()`。
+- 已提供 `wait_queue_wait()` 和 `wait_queue_wait_timeout()`，调用方可以等待条件成立，并在超时路径上获得失败返回值。
 - 已建立单 CPU interrupt-safe lock 基础，当前 `spin_lock_irqsave()` 会保存并关闭中断，`spin_unlock_irqrestore()` 会恢复原中断状态。
 - 已把 `kernel_thread_create()` 中的线程 id 分配和 run queue 入队纳入 interrupt-safe lock 保护。
 - 已建立 `sched_irq_exit()`，timer IRQ 只设置 `need_resched`，trap 的 IRQ 返回边界统一消费调度请求。
 - 已建立最小 DEAD 线程回收路径，调度前会释放非当前 DEAD 线程的内核栈和线程对象。
 - 已把调度代码按职责拆分为 `core.c`、`thread.c`、`wait.c`、`idle.c` 和私有 `sched.h`，并把当前阶段自测/演示线程移到 `kernel/selftest/sched.c`。
-- `scripts/check.sh` 已验证 `timer initialized`、`timer tick=1/2/3`、`scheduler initialized`、`kernel thread selftest ok`、timer 驱动线程轮转、`sched_sleep()` 和 wait queue wakeup。
+- `scripts/check.sh` 已验证 `timer initialized`、`timer tick=1/2/3`、`scheduler initialized`、`kernel thread selftest ok`、timer 驱动线程轮转、`sched_sleep()`、wait queue wakeup、条件等待和超时等待。
 
 后续扩展：
 
 - 把当前 `sched_irq_exit()` 继续收敛为更严格的 trap-frame aware interrupt-exit reschedule 模型，避免把普通线程栈切换入口长期当成完整抢占式切换。
 - 继续扩大 interrupt-safe lock 覆盖范围，明确可睡眠路径和不可睡眠路径的锁规则。
-- 为 wait queue 增加条件等待、超时等待和状态检查。
+- 为 wait queue 增加更严格的状态检查，并把条件检查与 wakeup 边界纳入明确锁规则。
 - 为线程退出增加更完整的生命周期状态、引用规则和最终释放约束。
 
 下一阶段：
diff --git a/include/tianole/sched.h b/include/tianole/sched.h
index 5533e21..47742d0 100644
--- a/include/tianole/sched.h
+++ b/include/tianole/sched.h
@@ -5,6 +5,7 @@
 #include <stdint.h>
 
 typedef void (*kernel_thread_entry_t)(void *arg);
+typedef int (*wait_condition_t)(void *arg);
 
 enum thread_state {
 	THREAD_READY,
@@ -44,6 +45,12 @@ void sched_yield(void);
 void sched_sleep(uint64_t ticks);
 void wait_queue_init(struct wait_queue *queue);
 void wait_queue_sleep(struct wait_queue *queue);
+int wait_queue_wait(
+	struct wait_queue *queue, wait_condition_t condition, void *arg);
+int wait_queue_wait_timeout(struct wait_queue *queue,
+	wait_condition_t condition,
+	void *arg,
+	uint64_t ticks);
 void wait_queue_wake_one(struct wait_queue *queue);
 void wait_queue_wake_all(struct wait_queue *queue);
 
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 979e92f..00f18d6 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -1,4 +1,5 @@
 #include <tianole/sched.h>
+#include <tianole/timer.h>
 
 #include "sched.h"
 
@@ -25,6 +26,35 @@ static void wait_queue_enqueue(struct wait_queue *queue, struct thread *thread)
 	queue->tail = thread;
 }
 
+static void wait_queue_remove(struct wait_queue *queue, struct thread *target)
+{
+	struct thread *prev = 0;
+	struct thread *thread;
+
+	if (queue == 0 || target == 0) {
+		return;
+	}
+
+	for (thread = queue->head; thread != 0; thread = thread->wait_next) {
+		if (thread == target) {
+			if (prev != 0) {
+				prev->wait_next = thread->wait_next;
+			} else {
+				queue->head = thread->wait_next;
+			}
+
+			if (queue->tail == thread) {
+				queue->tail = prev;
+			}
+
+			thread->wait_next = 0;
+			return;
+		}
+
+		prev = thread;
+	}
+}
+
 void wait_queue_sleep(struct wait_queue *queue)
 {
 	if (queue == 0 || current_thread == 0) {
@@ -36,6 +66,58 @@ void wait_queue_sleep(struct wait_queue *queue)
 	sched_yield();
 }
 
+int wait_queue_wait(
+	struct wait_queue *queue, wait_condition_t condition, void *arg)
+{
+	if (queue == 0 || condition == 0 || current_thread == 0) {
+		return -1;
+	}
+
+	while (condition(arg) == 0) {
+		wait_queue_sleep(queue);
+	}
+
+	return 0;
+}
+
+int wait_queue_wait_timeout(struct wait_queue *queue,
+	wait_condition_t condition,
+	void *arg,
+	uint64_t ticks)
+{
+	uint64_t deadline;
+
+	if (queue == 0 || condition == 0 || current_thread == 0) {
+		return -1;
+	}
+
+	if (condition(arg) != 0) {
+		return 0;
+	}
+
+	if (ticks == 0) {
+		return -1;
+	}
+
+	deadline = timer_ticks() + ticks;
+	while (condition(arg) == 0) {
+		uint64_t now = timer_ticks();
+
+		if (now >= deadline) {
+			return -1;
+		}
+
+		current_thread->wake_tick = deadline;
+		current_thread->state = THREAD_SLEEPING;
+		wait_queue_enqueue(queue, current_thread);
+		sched_yield();
+		wait_queue_remove(queue, current_thread);
+	}
+
+	current_thread->wake_tick = 0;
+	return 0;
+}
+
 void wait_queue_wake_one(struct wait_queue *queue)
 {
 	struct thread *thread;
@@ -51,7 +133,9 @@ void wait_queue_wake_one(struct wait_queue *queue)
 	}
 
 	thread->wait_next = 0;
-	if (thread->state == THREAD_WAITING) {
+	if (thread->state == THREAD_WAITING ||
+		thread->state == THREAD_SLEEPING) {
+		thread->wake_tick = 0;
 		thread->state = THREAD_READY;
 	}
 }
diff --git a/kernel/selftest/sched.c b/kernel/selftest/sched.c
index a983a79..7cf9924 100644
--- a/kernel/selftest/sched.c
+++ b/kernel/selftest/sched.c
@@ -65,6 +65,16 @@ static void scheduler_demo_entry(void *arg)
 }
 
 static struct wait_queue demo_wait_queue;
+static struct wait_queue condition_wait_queue;
+static struct wait_queue timeout_wait_queue;
+static int condition_ready;
+
+static int condition_is_ready(void *arg)
+{
+	int *ready = arg;
+
+	return *ready != 0;
+}
 
 static void wait_queue_demo_waiter(void *arg)
 {
@@ -85,6 +95,45 @@ static void wait_queue_demo_waker(void *arg)
 	wait_queue_wake_one(&demo_wait_queue);
 }
 
+static void condition_wait_demo_waiter(void *arg)
+{
+	(void)arg;
+
+	early_log_puts("condition waiter sleeping\n");
+	if (wait_queue_wait(&condition_wait_queue,
+		    condition_is_ready,
+		    &condition_ready) != 0) {
+		panic("condition wait failed");
+	}
+	early_log_puts("condition waiter woke\n");
+}
+
+static void condition_wait_demo_waker(void *arg)
+{
+	(void)arg;
+
+	early_log_puts("condition waker sleeping\n");
+	sched_sleep(5);
+	condition_ready = 1;
+	early_log_puts("condition waker wake_all\n");
+	wait_queue_wake_all(&condition_wait_queue);
+}
+
+static void timeout_wait_demo_waiter(void *arg)
+{
+	int never_ready = 0;
+
+	(void)arg;
+
+	early_log_puts("timeout waiter sleeping\n");
+	if (wait_queue_wait_timeout(
+		    &timeout_wait_queue, condition_is_ready, &never_ready, 3) !=
+		-1) {
+		panic("timeout wait did not time out");
+	}
+	early_log_puts("timeout waiter timed out\n");
+}
+
 void sched_demo_start(void)
 {
 	struct thread *first = kernel_thread_create(
@@ -95,12 +144,23 @@ void sched_demo_start(void)
 		kernel_thread_create("waiter", wait_queue_demo_waiter, 0);
 	struct thread *waker =
 		kernel_thread_create("waker", wait_queue_demo_waker, 0);
+	struct thread *condition_waiter = kernel_thread_create(
+		"condition-waiter", condition_wait_demo_waiter, 0);
+	struct thread *condition_waker = kernel_thread_create(
+		"condition-waker", condition_wait_demo_waker, 0);
+	struct thread *timeout_waiter = kernel_thread_create(
+		"timeout-waiter", timeout_wait_demo_waiter, 0);
 
-	if (first == 0 || second == 0 || waiter == 0 || waker == 0) {
+	if (first == 0 || second == 0 || waiter == 0 || waker == 0 ||
+		condition_waiter == 0 || condition_waker == 0 ||
+		timeout_waiter == 0) {
 		panic("scheduler demo thread creation failed");
 	}
 
 	wait_queue_init(&demo_wait_queue);
+	wait_queue_init(&condition_wait_queue);
+	wait_queue_init(&timeout_wait_queue);
+	condition_ready = 0;
 	early_log_puts("scheduler starting\n");
 	sched_yield();